Insulating bushing



Sept. 30, 1930. G. A. BURNH'AM' INSULATING BUSHING Original Filed Aug. 20. 1927 ji 'verfibr'. W 61 Patented Sept. 30, 1930 UNITED, STATES? enema a. BUBNBAM, or sevens, massaqnusmrs, assronoa 'ro oomarr amoraxcan muracruamo cameraman, OF SOUTH BOSTON, MASSACHUSETTS, A

TION or mssaonusn'r'rs nsumri m nus nme Application fleql gug ust 20, 19!, Serial 170. 214,275. Renewed Imag ne.

This invention relates to electric insulators as insulating bushings especially adaptedyalthough not necessarily limited, for use in high tension "oil immersed switches and is a con- 6 tinuation in part of my copending application Serial, No. 102,069, filed; April 14, 1926.

The terminals of an'electric switch must have sufficient spacing to prevent flash-overs between them, and where air is the insulating medium; the terminals must necessarily spaced widely apart to-provide sufiicient insulation, if high voltages are employedy To provide the requisite spacing with vertically disposed insulating bushings would necessi l tateswitchcaSings of a'prohibitive size; so it hasbeen common practice to obtain the desired'spacing at the upper exposed ends of the bushing by inclining the bushings outwardly. This construction,while providing an increased spacing at the top of'the insulator, must necessarily decrease'the spacing at the lower end of the insulator; To a certain extent, this may be. permissible since the lower exposed terminals of the insulator are bushings are inclined to' any greatextent, the lateral dimensions of the switchcasing must be increased to maintain'a safe spacing of the lower terminals I I Consequently, an object of this invention isthe provision of' a'n insulating bushing so arranged that, when two or'more of them are used as the terminals of an oil immersed electric switch or other similar apparatus, a. suitable close spacing is'provided between them, at the lower ends thereof under the oil while a suitable wide .space is provided between; them at their upper and air-exposed ends. f

A further objectof'the invention isthe provision. of an oil or compound filled insu- I I lating bushing comprising two angularly related tubular insulating isections connected rigidly together in communication with a bare conductor-extended through said sections and bent'in' correspondence with said sections, and rovided' with exposed circuit terminals at t e ends of the bushing, com bined with means disposed in the interior of 6 the bushing and in engagement. both with tor spacin'g memhe'r withinthehushing;

upper and. lower sections so that said insubushing embodyingthis invention. 1

Fig. 2 isa sectional. elevation through: the

.insulator'ofi-Figa 1.

Fig; 3 is a section' along line of Fig. 2. F ig; 4 iswa'sectionaldetail illustrating a modification in the-position of the conduc- The insulating bushing embodying this invention comprises the straight upper: tubula-n insulating body or she'll-.10, the intentio diate tubular attaching member'or sleeve 12 and the lower: straight tubularinsulator body or shell 14-, The .uppershell .10 is adapted to be exposedto the atmosphere and 'may be provided. with the usual petticoats j 16'. The lower shell His-adapted totbe im- 35 immersed in oil; but it is evident'that if the this invention, the tubular sleeve 12 is bent intermediate its ends to. follow a regular curve and to provide angularly-related lating shells connected with the endsthereof are angularly inclined withrespect-to each other.- The upper end of .said'bent metal sleeve 12 is provided with an attaching flange 18and the lower end of said shell is provided with an attaching flange 20; A clamping flange 22 is cemented or otherwise secured to surround thebottom end of the upper insulating shell 1.0 and isrigidly secured detachably upon the flange 18 of said sleeve 12 and in alignment withthe passage through said sleeve by bolts 24:. The upper end of the lower insulating shell 14;. has a similar clamping. flange 26 cemented. there- 95 to; and said'fiangelis secured to the flange 20 of the sleeve 12 by bolts 28 sothatthe passage in said tube 14 is in. alignment with the passage; in saidsleeve 12. The joints betweenthe insulating shells and the sleeve 12 are made fluid tight in any suitable or usual manner.

The bushing is adapted to be received in the aperture 30 of the containing casing 32 of some suitable electrical'apparatus which may be of the sleeve is bolted to said casing able. bolts 3fl. The insulating bushing thus described is adapted to be filled with oil'and is provided with an oil reservoir 36 atthe upper end of the upper insulating. shell.12

'it'is obvious that more than one disc can be .used if desired." WVhile Iprefer to locate the disc as shown in Fig. 2, it may be convenient which oil reservoir may be secured to said shell in any 1suitable-;manner and is charac terized by having a transparent side wall through which theheightof oil in theinsulator is visibleas is usual in some types of oil filled bushings. 4 v I a A conductor 38 is extended through said bushing in axial "alignment therewith and said conductor is providedfwith an upper straight portion '38 which is conformed with the straight portion'offthe shell 10 an'dthe sleeve 12; an intermediatebent porti 38b Whichlies axiallywithin the sleeve 12"'and able switch member of anelectric switch or is conformed with thebent portion thereof;

a lower straight portion 38 which lies axially within the straight lowershell 14: and the straight-portionof the sleeve 12. Said conductor may be" either solid or tubular but preferably is relatively rigid and self-supporting although it can be otherwise as Will be set forth hereinafter. The upper end of said conductor can be externally screw-threaded "as shown and pass throughthe upper end of'the oil reservoir 36 and'be provided'with clamping nuts 40 thereon for connectionwith a line conductor. 'The lower end ofsaidconductor is provided w ith'screv threads 42 and is threadedinto a shouldered stud {l4 whic'his secured in'an oil tight manner through ametalcap46 which iscemented or otherwise secured in an oil=tight manner to the lower end of the insulating shell 14, The lower end of said stud is externally screw threaded and-provided with a conta'ct block 48'to be engaged by the movit may be arranged for connection with the circuit lead of some suitableelectrical apparatus, as the casemay be.

Means are providedito in its axial position within the bushing and against" undue lateral displacement therefrom. As shown in Fig. 2,said'means.com

prises a disk 5070f some suitableinsulating material which is received in an annular recess 52 formed intheupper face of the flange l8 of-the metal sleeve 12 and held in such a location by the insulating shelllO .which is disposed thereabove. Said insulating disc 50 is providedwith an aperture therein through which thefconductor is passed and conseq uently holds said cOnductorfrom displacement-out of the axial position illustrated. The bushing is adapted to be filled with oil an electric switch and the flange 18 by suithold the conductor to some level which will be visible in the oil reservoir 36 thereby to insulate the conductor, especially from the metal sleeve 12, and also to exclude air from the interior of the bushing about said conductor. The disc 50 is provided with one or more passages 51 therethrough which provides for free communication of the bodies of oil above and below 'said'discs. But one disc 50-is'necessary to maintain the conductor in position Within the walls of the bushing, although to place it in oneof the insulatingshells and Ihave shown a disc 50 similar in its vital aspects to the disc 50 disposed in the lower insulating shell Hand in engagementboth with said shell and with the conductor 38 and held in position within said shellby engagement with the tapered inner face thereof. i

In Fig. l, thedisc 50 is disposed within the metal shell 12 at the bend thereofgas is showninmy above named copending application. 7 i

While I prefer to use a rigid conductor, I can, if convenient, use a more or lessfiexible conductor and'support it against displacement from axial position by the use .of a

plurality of insulating spacing discs 50 and50t.

r The construction may be otherwise modified' without departing from the spirit of n the invention.

Iclaim: 1. An insulating intermediate its ends, a conductor extended axially through said bushing and having bend conformed withthe bend of said bushing and-having terminal members at the ends of the bushing, and a spacer member dis posed within said bushing and in engagement bushing having a bend both with the wall of said bushing and-with,-

said conductor and arranged to hold said conductor against lateral displacement within said bushing; V

' 2. An insulating bushing having a bend intermediate its ends,a conductor extended 5i within said bushing and in engagement both with the wall of said bushing and with said conductor and arranged to hold said conductor against lateral displacement within said bushing, said spacer member being provided with a passage'therethrough between said conductor and the .wall'of said bushing to admit of free fluid communication ofthe fluid bodies above and. below said spacer member.

3; An oil a bend intermediate its ends, a conductor exfilled insulatingbushing having tended axially within said bushing having a bend conformed with the bend of said bushing and havin exposed terminal members at the ends oft e bushing, and an insulating spacer member disposed within said bushing intermediate its ends and having engagement witlrthe wall of said bushing and also with said conductor intermediate its ends and arranged to restrain said conductor in its aforesaid position.

4. An oil filled insulating bushing having a bend intermediate its ends, a conductor extended axially within said bushing having a bend conformed with the bend of said bushing and having exposed terminal members at the ends of the bushing and an insulating spacer member disposed within said bushing intermediate its ends and having engagement with the wall of said bushing and also with said conductor intermediate'its ends and arranged to restrain said conductor in its aforesaid position, said insulating spacer member having a passage therethrough providing free oil communication between the bodies of oil above and below it.

5. An oil filled bushing having a bend intermediate its ends, a rigid conductor extended axially within said bushing and having a bend intermediate its ends conformed with the bend of said bushing and having terminal members at the end of the bushing, and a spacer disc disposed within said bushing and in engagement with the wall thereof and also with sald conductor and arranged to restrain said conductor against displacement from the aforesaid position, said conductor being bare, and a body of oil disposed within said bushing around said conductor providing the insulation therefor.

6. An oil filled insulating bushing comprising a tubular metal sleeve having a bend intermediate its ends, tubular insulating shells attached to the ends of said sleeve and angularly inclined with respect to each other, a bare conductor extended axially within said bushing and having a bend therein conformed with the bend of said bushing and having exposed terminal members at the ends of the bushing and in contact with the oil in the bushing, and an insulating spacer disc carried by said metal sleeve and arranged in engagement with said conductor to restrain it against lateral displacement.

7. An insulating bushing comprising upper and lower tubular insulating shells, a metal sleeve connecting said shells, an insulating disc disposed in the upper end of said metal sleeve, a conductor extended axially through said bushing and said disc and having exposed terminal members at the ends of the bushing, and a body of oil in said bushing providing the insulation for said conductor.

In testimony whereof I have signed my name to this specification.

GEORGE A. BURNHAM. 

